My 1652 is a tunnel but the transom is 23" with a 2-1/2" tunnel so I have the Merc short shaft jet mounted 2-1/2" above the transom to tuck it into the tunnel at the right height. A short shaft motor would be perfect for a 20" transom but you would need to use the lift plates to mount a 20" shaft motor. That might put the tiller handle up higher than you would be comfortable with. I have a center console so I can't comment on the tiller but I sat in my boat to get a feel for it and it would depend on whether the motor needs transom wedges to get the motor tucked in (I needed the wedges to keep mine from porpoising). The angle of the motor tucked in would cause the tiller to be angled upwards and a 20" shaft motor would be 5" higher than mine currently is mounted and it would definitely be uncomfortable for me, but I'm 5' 6" tall. So there are a lot of variables to figure out what right tiller height is for you.